Zotero

Note: You need at least Zotero 6 to access these features. 

You can view and annotate PDFs inside Zotero by double-clicking on the reference or file in your library. PDFs open in a separate tab.

The details pane opens automatically, defaulting to the reference's Info tab.

You can open the left-hand sidebar by tapping the arrow icon at the top left of the toolbar. This allows you to view your annotations as you create them, as well as the PDF's pages and outline (if available).

The PDF Reader has several options for annotation including highlighting, sticky notes, and selecting areas (essentially a screenshot).

This screenshot displays a variety of colors and options for annotating in the PDF Reader.

Annotations live as metadata associated with a specific PDF in your library and are different from Notes. Notes appear in your library either as a child note, which belongs to a specific item, or as a standalone note.

You can add some or all annotations on a PDF to a Zotero note, so you can see them when viewing your library (if you want to!). Once you've added annotations to your PDF, tap the plus sign (+) in the notes pane and choose Add Item Note From Annotations.

Existing annotations will now appear in the note with their citations. If you add more annotations later and wish to include them in the same note, select it in the notes pane and right-click the annotation. You can also simply drag and drop the new annotation into the note.